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What is PWM Dimming For LED Driver?

In order to avoid LED color temperature deviation caused by current changes, the most effective method is PWM dimming (Pulse.Width.Modulation). In this dimming method, the brightness of the backlight is actually fixed. It adjusts the screen brightness by controlling the periodic turning on and off of the backlight. 

1,What is PWM dimming?

PWM dimming is a dimming technology that uses simple digital pulses to repeatedly switch LED drivers on and off. The user’s system only needs to provide wide and narrow digital pulses to simply change the output current to adjust the brightness of the LED. The advantage of PWM dimming is that the dimming range is large. As long as the bandwidth is sufficient, any analog value can be encoded using PWM. PWM dimming can accurately control the brightness of the LED while also ensuring the chromaticity of the LED light.

what is PWM


2. What is PWM dimming working principle?

The control method is to control the on and off of the inverter circuit switching device so that the output end gets a series of pulses with equal amplitude, and these pulses are used to replace the sine wave or the required waveform. That is, multiple pulses are generated in half a cycle of the output waveform, so that the equivalent voltage of each pulse is a sinusoidal waveform, and the obtained output is smooth and has few low-order harmonics.


3, How to do PWM dimming?

LED is a diode, which can achieve fast switching, and the speed can be as high as a meager profit, which is unmatched by any light-emitting device. Therefore, as long as the power supply is changed to a pulse constant current source and the pulse width is changed, the brightness can be changed. This method is called pulse width modulation (PWM) dimming.

The figure below shows the waveform of this pulse width modulation. If the pulse period is tpwm and the pulse width is ton, then its working ratio D (or hole ratio) is ton/tpwm. Changing the working ratio of the constant current source pulses can change the brightness of the LED.

The method to achieve PWM dimming is to insert a MOS switch tube in series with the LED load, and the anode of this string of LED is powered by a constant current source.

Then a PWM signal is added to the gate of the MOS tube to quickly switch this string of LED on and off. Thus achieving dimming. There are also many constant current chips with a PWM interface. It can directly accept the PWM signal and then output it to control the MOS switch tube.

How to do PWM dimming



4, Advantages and disadvantages of PWM dimming

1. Efficiency: PWM dimming can adjust the brightness of the light source by quickly switching the power supply voltage, so when the brightness is reduced, the input power of the power supply will be effectively reduced to improve energy efficiency.

2. Brightness stability: By controlling the PWM dimming period and duty cycle, you can obtain a very stable brightness output, which can provide high-quality dimming effect and light control.

3. Wide dimming range: PWM dimming can achieve a very wide dimming range, from 0% to 100% brightness.


1. Potential visible flicker: Since PWM dimming achieves the dimming effect by rapidly switching the power supply voltage, when the dimming frequency is lower than the frequency perceived by the human eye, visible flicker may be caused.

2. Not applicable to some lamps and electronic equipment: PWM dimming is sensitive to electromagnetic interference for some lamps or electronic equipment, such as some LED lights that may emit noise.



5, Does pwm dimming really hurt your eyes?

PWM dimming does not directly harm the eyes. However, low frequency PWM dimming (generally below 100Hz) may cause discomfort or eye strain to the human eye, depending on the individual’s feelings and sensitivity.

At low frequency PWM dimming, the human eye may perceive the flicker or flutter of the light source. This can lead to symptoms such as eye strain, eye discomfort, blurred vision, or headaches. For some people, this flicker may also cause other discomfort or affect the ability to concentrate.

However, high frequency PWM dimming (generally above 200Hz or more) can eliminate visible flicker. It can provide a more stable, smooth and perceptionless dimming effect, thereby reducing potential eye strain issues.

Therefore, in order to reduce potential discomfort or eye strain, it is beneficial to use high frequency PWM dimming or other flicker-free dimming methods. At the same time, personal feelings and sensitivity can also affect the perception of flicker, so different people may have different experiences.

It is best to choose low flicker and high quality dimming technology, especially for people who work or use in dimming environment for a long time, in order to protect the health of the eyes.



6, Do you have PWM dimming driver?

Sure, As a professional led driver manufacturer in China, Beon have High quality dimming power supply- PWM dimmable driver.

Excellent quality and reasonable price!

BEON brand dimming led driver, focusing on dimming power supply, can provide high quality products according to customer needs, welcome to inquire.

beon hot selling led drivers




BEON: A Reliable Provider of PWM LED Dimming Driver

Beon, with its growing reputation, experienced workforce, and updated methods, is your trusted source for the highest quality dimmable LED drivers.

We provide;

Constant current dimmable


  • Constant Current Output from 50Watt to 300Watt
  • IP67 Waterproof for outdoor lighting and horticulture lighting
  • Supply Voltage: 180-265Vac or 100-277Vdc, 380Vac for 2 hours
  • Great Surge Immunity 10kV
  • -45℃Cold Ambient Startup (Optional)
  • 50,000Hour Life @ Tc=75℃ & 5 Year Warranty @ Tc<=75℃
  • CE/CB/CCC SELV Output
  • Safety according to EN 61347-1, 61347-2-3, 61347-2-13, 62384
All our LED drivers,  all support PWM dimming signal.
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